Despite frigid Florida temperatures, water too warm to kill red tide, experts say

The chill that is essentially freezing Floridians to the core probably won’t have a big effect one of the state’s least popular nautical residents: red tide.

Despite this, the bloom that had been stinking up Southwest Florida shores since at least mid-November appears to be crawling north.

According to the Florida Fish and Wildlife Conservation Commission’s red tide report released Friday, the Karenia brevis organism was found in background concentrations in one sample near Mullet Key in Pinellas and in background to medium concentrations in the 15 samples collected earlier this week in Sarasota, with the hardest hit areas from Brohard Beach to Boca Grande Pier in Charlotte.

Medium concentrations mean that there are between 100,000 and 1 million K. brevis cells per liter of water. Fish kills and respiratory irritation were also reported in the red tide bloom from Sarasota to Lee counties.

“This cold weather will not likely, standalone, have an effect,” said Tracy Fanara, the environmental health program manager at Mote Marine Laboratory. K. brevis cells get stressed when water temperatures dip below 60 degrees Fahrenheit or above 86 degrees Fahrenheit, she said.

While the air temperature at Coquina Beach read nearly 54 degrees on Wednesday afternoon, the water clocked in as 11 degrees warmer. Two days later, water temperatures danced around red tide’s breaking point.

The factors that will have a greater effect on red tide than short-term cold weather are winds and currents, Fanara said. And because of the bloom’s patchy nature, conditions at one part of a beach may not reflect what they are on another portion.

“The cold water, if anything, it might suppress it because plants grow more slowly in cold water,” said Robert Weisberg, principal investigator with the University of South Florida’s Ocean Circulation Group, which coordinates with FWC on its red tide reports.

Beachgoers can help input real-time red tide data with Mote’s CSIC, or Citizen Science Information Collaboration, app that can be found in the App Store or on Google Play. Those observing the effects of red tide, like discolored water or dead fish, can fill out a form to report red tide as well as view a map of other reports.

Researchers think that red tide, a toxic algal bloom of naturally-existing K. brevis, starts to bloom in the continental shelf several miles offshore on the ocean floor before appearing on the water’s surface near beaches. Of course, he said, additional sampling offshore takes funding.

For now the standard near shore water samples are often too late to be predictions, Weisberg said, when intense accumulations can cause coughing, watery eyes and fish kills.

“If we know it’s happening offshore, we can better position what may appear later on,” he said.

This story was originally published January 3, 2018 at 5:17 PM with the headline "Despite frigid Florida temperatures, water too warm to kill red tide, experts say."